Ich or Velvet? what next, need help asap.

[D70Challenger]

Hello all, new to the forums. I have a 72 gal tank with a 20 gal sump. I have 2 clowns and on monday bought a yellow tang. I had 3 clowns but one died and the other 2 went into hiding for about 2 weeks. when i got the tang on monday the clowns came out and one was absolutley covered in what appeared to be ich. it spread to the other clown and now the tang. ive had aquariums before and lost fish to ich multiple times. Im confused this time, because when most of my fish have had ich they die insanley fast. but these 3 fish have had it for almost a week and are showing no signs of traditional ich or velvet. they are not twitching, scratching, or any other standard signs. ive tried the medication "Ich-X" but does not seem to have worked. any help on what my next steps to save my fish are? i have no coral so i can dose my tank with any meds i want for the time being. ...actually during this posting i noticed the tang is beginning to scratch. any help on some steps to take? i havent taken the fish out individually to quarantine them as i have no place to put them and dont feel i could catch the tang if i wanted to. any help would be greatley appreciated. i need to know asap to save their lives.

[Chasman]

You should move your post to the Saltwater (Fish Only) area or the Care and Health thread. You will get much better and faster responses.